2f11cb4c4c
AudioHAL and SoundtriggerHAL is separeted HAL but running in thread with same process id. So, if both HAL try to open netlink socket using uevent_open_socket(), secondly opening socket receives already-in-use error. To prevent situation, set 0 to socket port id. By the LINUX man page, "The kernel assigns the process ID to the first netlink socket the process opens and assigns a unique nl_pid to every netlink socket that the process subsequently creates." Bug:163008274 Test: tested by opening netlink socket in AudioHAL and SoundtriggerHAL both. Signed-off-by: Gyeongtaek Lee <gt82.lee@samsung.com> Change-Id: I5f9859e8dac749bf5d0998e825043c9988c202ba
136 lines
3.9 KiB
C++
136 lines
3.9 KiB
C++
/*
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* Copyright (C) 2011 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <cutils/uevent.h>
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#include <errno.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <string.h>
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#include <strings.h>
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#include <sys/socket.h>
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#include <sys/un.h>
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#include <unistd.h>
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#include <linux/netlink.h>
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extern "C" {
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/**
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* Like recv(), but checks that messages actually originate from the kernel.
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*/
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ssize_t uevent_kernel_multicast_recv(int socket, void* buffer, size_t length) {
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uid_t uid = -1;
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return uevent_kernel_multicast_uid_recv(socket, buffer, length, &uid);
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}
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/**
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* Like the above, but passes a uid_t in by pointer. In the event that this
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* fails due to a bad uid check, the uid_t will be set to the uid of the
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* socket's peer.
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*
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* If this method rejects a netlink message from outside the kernel, it
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* returns -1, sets errno to EIO, and sets "user" to the UID associated with the
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* message. If the peer UID cannot be determined, "user" is set to -1."
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*/
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ssize_t uevent_kernel_multicast_uid_recv(int socket, void* buffer, size_t length, uid_t* uid) {
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return uevent_kernel_recv(socket, buffer, length, true, uid);
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}
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ssize_t uevent_kernel_recv(int socket, void* buffer, size_t length, bool require_group, uid_t* uid) {
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struct iovec iov = {buffer, length};
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struct sockaddr_nl addr;
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char control[CMSG_SPACE(sizeof(struct ucred))];
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struct msghdr hdr = {
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&addr, sizeof(addr), &iov, 1, control, sizeof(control), 0,
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};
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struct ucred* cred;
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*uid = -1;
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ssize_t n = TEMP_FAILURE_RETRY(recvmsg(socket, &hdr, 0));
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if (n <= 0) {
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return n;
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}
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struct cmsghdr* cmsg = CMSG_FIRSTHDR(&hdr);
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if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
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/* ignoring netlink message with no sender credentials */
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goto out;
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}
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cred = (struct ucred*)CMSG_DATA(cmsg);
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*uid = cred->uid;
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if (addr.nl_pid != 0) {
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/* ignore non-kernel */
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goto out;
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}
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if (require_group && addr.nl_groups == 0) {
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/* ignore unicast messages when requested */
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goto out;
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}
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return n;
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out:
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/* clear residual potentially malicious data */
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bzero(buffer, length);
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errno = EIO;
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return -1;
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}
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int uevent_open_socket(int buf_sz, bool passcred) {
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struct sockaddr_nl addr;
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int on = passcred;
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int buf_sz_readback = 0;
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socklen_t optlen = sizeof(buf_sz_readback);
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int s;
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memset(&addr, 0, sizeof(addr));
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addr.nl_family = AF_NETLINK;
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addr.nl_pid = 0;
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addr.nl_groups = 0xffffffff;
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s = socket(PF_NETLINK, SOCK_DGRAM | SOCK_CLOEXEC, NETLINK_KOBJECT_UEVENT);
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if (s < 0) return -1;
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if (setsockopt(s, SOL_SOCKET, SO_RCVBUF, &buf_sz, sizeof(buf_sz)) < 0 ||
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getsockopt(s, SOL_SOCKET, SO_RCVBUF, &buf_sz_readback, &optlen) < 0) {
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close(s);
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return -1;
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}
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/* Only if SO_RCVBUF was not effective, try SO_RCVBUFFORCE. Generally, we
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* want to avoid SO_RCVBUFFORCE, because it generates SELinux denials in
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* case we don't have CAP_NET_ADMIN. This is the case, for example, for
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* healthd. */
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if (buf_sz_readback < 2 * buf_sz) {
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if (setsockopt(s, SOL_SOCKET, SO_RCVBUFFORCE, &buf_sz, sizeof(buf_sz)) < 0) {
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close(s);
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return -1;
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}
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}
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setsockopt(s, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
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if (bind(s, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
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close(s);
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return -1;
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}
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return s;
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}
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} // extern "C"
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